The present invention refers to petroleum industry and can be used for production of hydrocarbons in order to increase daily flow rates and prolong economical life of wells. The present invention can be used in oil wells with high and medium gas oil ratio (GOR), with an active solution gas drive and gas cap mode and gas or/and water cones in the formation in order to increase daily oil flow rates and recovery factor.
A method of well operation with a flow control device is known according to U.S. Pat. No. 5,893,414. The main part of the device is a set of axially vertically aligned tubes of different diameters and lengths, representing a multiparametric hydrodynamic system, which establishes a certain precalculated bottomhole pressure below the device, in order to decrease gas blockage of the near bottomhole zone of the formation and to provide a homogenous fluid flow to the surface. Above the device a forced fluid degassing takes place, creating two-phase gas-liquid emulsion, which aids fluid lift within the well.
A gas lift method of fluid lift in the well to the surface is further known. Gas lift is one of the efficient methods of well operation after its natural flowing stops due to a reduced reservoir pressure. In standard cases, gas is injected into the annulus between the casing and the tubing and flows into the tubing through gas lift valves. Fluid density in the well decreases and weight of the tubing fluid column reduces. As a result, bottomhole pressure decreases, causing, in some cases, a temporary increase in flow rates.
In the process of active solution gas drive and coning, gas and water saturation of the drainage zone increase, affecting oil filtration into the well. Oil viscosity increases, gas blocks the near bottomhole zone of the reservoir, and oil permeability of the reservoir decreases. As a result, oil productivity of the well reduces. Gas lift often worsens the above mentioned processes by decreasing bottomhole pressure considerably lower than saturation pressure, due to injection of big volumes of gas. As a result, oil rapidly degasses in the near bottomhole zone, causing all aforementioned negative effects.
In order to reduce gas and water flow into the well, operators often reduce the diameter of wellhead choke. Wellhead pressure increases, as well as bottomhole pressure, and flow within the formation redistributed, so that oil flow rates somewhat increase. At the same time, reduction of the diameter of wellhead choke may affect the process of lift, due to an increased pressure in the tubing (both wellhead pressure and pressure at the gas lift valves), weight of the fluid column also increases, and significantly more injection gas and pressure are required to provide fluid lift to the surface. Thus, in a gas lift, well bottomhole pressure regulation from the wellhead cannot always provide lift optimization.
It is therefore believed that the existing methods and systems for production of hydrocarbons can be further improved.